To dilate or cause to expand; an archaic or rare form meaning to make wider or larger.
From Latin dilatatus, past participle of dilatare. This appears to be a back-formation or variant of 'dilate,' sometimes found in older technical or medical texts but largely superseded by 'dilate.'
Dilatate is basically a redundant cousin of 'dilate'—both come from the same Latin root, but 'dilate' won out in English, leaving 'dilatate' as a museum piece in scientific vocabularies.
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